Applicator pad



1967 N. L. WATKINS, JR 3,334,374

APPLI CATOR PAD Filed Dec. 28, 1964 I N VE NTOR. Mg/M/v/a LMTK/MSIJQUnited States Patent 3,334,374 APPLICATOR PAD Nathaniel L. Watkins, Jr.,White Bear Township, Ramsey County, Minm, assignor to Minnesota Mining &Manufactoring Company, St. Paul, Minn., a corporation of Delaware FiledDec. 28, 1964, Ser. No. 421,479 4 Claims. (Cl. 15539) This applicationrelates to applicator pads for applying a liquid agent to an object orsurface, the pads being dry in storage but containing within them areadily released supply of the liquid agent. Common examples of the jobswhich the pads comprising this invention are adapted to simplify areremoving stains or soils from clothing; cleaning or polishing metal orother surfaces or applying protective coatings over them; lubricatingsmall articles; polishing shoes; removing fingernail polish; etc.

The novel applicator pads shorten and simplify these jobs. In place ofbuckets and mops, bottles and cloths, and similar customarycombinations, only a single item that may be kept in one place isrequired. No preliminary steps prior to application of the liquid areneeded and the correct measure of liquid is quickly applied in thedesired location. Further, the pads are tidy, dry, and may beconveniently stored in an orderly manner. There is no chance forspilling or dripping during performance of the job. Another advantage ofthe applicator pads of the invention is that they may be storedindefinitely Without deterioration or reaction of the liquid agent.

In general, an applicator pad of the invention includes a flexible,compressible, sealed receptacle containing pressure-rupturable capsulesfilled with the desired liquid agent. A convenient form of receptacle isa thin, flat pouch havingfront and back Walls united at their peripheraledges. At least one area of the walls forming permeable web readilyconformable to the surface to which liquid is to be applied. When thereceptacle is compressed as by being pressed against the object to betreated, the capsules are crushed and the liquid agent released. Thereleased agent penetrates the permeable portion of the receptacle andcovers or soaks into the object against which the pad is pressed.

An exemplary applicator pad of the invention is shown in section in thedrawing. The flat, thin, flexible pouch pictured there comprises aliquid-impermeable back Wall 11, typically a polymeric film, and aliquid-permeable front wall 12, typically a nonwoven fabric of fibers ofa material such as a reconstituted cellulosic or cotton linters bondedwith an organic resin. Metal foils, paper sheets, and various wovenfabrics might also be used, and the liquid-permeable wall might be aperforated sheet when used with capsules of large enough size. In manycases an absorbent material is desirably used as the front, permeablewall. In the'illustrated pouch, the Walls 11 and 12 are attached aroundtheir edges by heat sealing, though they might also be attached withadhesive or tape, or by sewing, etc.

The liquid-impermeable back wall 11 keeps the users hand dry and directsall the liquid applied through the permeable wall, but in some uses thewhole pouch material might be liquid-permeable. A rather thin front wall12 is desirable for the most immediate and complete application of theliquid contents. The porosity and thickness may be varied depending onthe particular application, thicker webs being desirable, for example,where more rubbing or bufling may be used. Abrasives can also beincorporated within either the porous or impermeable web where desired.

The thin, flat character of the pouch 10 assures distribution of thecapsules in a thin layer over the surface of application. Thus, thereleased liquid from the capsules is ice more quickly and completelyavailable since it need not soak around other capsules or crushedcapsule shells. Other receptacles, preferably having such a thincompartment, may also be used, such as thin boxes with a permeable baseand flexible or depressible top, hollowed out sponges or pads, etc.

Pressure-rupturable capsules, comprising thin, self-supporting,polymeric shells around particles of the desired liquid agent, areplaced within the pouch before it is finally sealed. The capsules may beformed with a wide variety of aqueous or organic liquid fills by manyprocesses known to the art, as for example as described in the GreenPatent No. 2,800,457, issued July 23, 1957, or in Raley Patent No.2,766,478, issued Oct. 16, 1956, or by other known techniques. Tough,useful capsules having good storage and handling characteristics havebeen found to be those having aminoplast polymer shell walls aroundfinely divided particles of the liquid agent. Such capsules may be madeby the procedure described in the copending application of Gale W.Matson, U.S. Ser. No. 175,394, filed Feb. 26, 1962, and now abandoned.

The manufactured capsules are dry, and in small microscopic sizes(microcapsules) may have the appearance of a fine powder; in largersizes the capsules are visually observable as such to the unaided eye..The aminoplast shelled capsules may be stored indefinitely withoutdeterioration, evaporation or reaction of their liquid contents.Typically they are impervious to moisture.

Under moderate pressure the capsules burst, discharging their liquidfill. In using the pads, the liquid agent may be freed by such methodsas squeezing the pad between the fingers preliminary to application orpressing the pad against the object to which the liquid is to beapplied. As the pad is pressed or rubbed against the object, thereleased liquid penetrates the porous facing member 12 and soaks intothe object or is distributed over its surface.

For good results the capsules should have an average diameter in therange of 2001000,u.. Capsules more than 1000 in diameter are lessdesired because to make them handleable in manufacturing and processingthey must have rather thick, strong shells that hinder easy rupture ofthem in an applicator pad. At sizes smaller than 200/L, the capsulesbecome rather difficult to rupture by hand pressure. Further, with smallcapsules the shells comprise too large a proportion, and the usableliquid too small a proportion, of the pouch contents. Since the capsuleshell acts as an adsorbent, small capsules with their accompanying largesurface area of shell upon rupture may also be disadvantageous ascausing too great an adsorption of liquid released from the capsules.Preferably the capsules are in a range of about 300600,u. in diameter.

The liquid fill normally comprises about 50 to 99 or more weight percentof the capsules. Capsules are included in the pouch 10 in an amountprincipally determined by the amount of liquid that is normally neededor desirable in a single application of the pad. As previously notedhowever, the amount of capsules should be such as not to become such athick layer in the pouch that the pouch becomes unwieldly. For capsulesbetween 200 and 600 a pouch having an impermeable back wall should beless than about and preferably less than about in thickness.

For certain cleaning applications such as dry cleaning, the brokencapsule shells may be of advantage if they adsorb the loosened soil fromthe clothing fabric. Addi-. tional adsorbents, such as clay, may beadded to the pouch to increase adsorption.

Dry cleaning solvents, mineral spirits, detergents, abrasive liquids,lubricants, polishes, tarnish preventing agents, and pesticides areincluded among the variety of oils, solvents, and reactive chemicalsthat may be usefully employed as liquid fills in the capsules of thepads of this invention. The particular agent of a class chosen willdepend on the needs of the particular application. For example, for drycleaning purposes a liquid fill of the capsules should be chosen thathas a broad spectrum solvency of oils, chemical inertness towardclothing fabrics, low vapor toxicity, and an appropriate evaporationrate so that the agent remains liquid during the time of application butevaporates sufficiently fast to permit a quick use of the materialcleaned. Typical dry cleaning fluids include perchloroethylene andtrichloroethylene.

In one specific embodiment of the invention a pouch as illustrated inFIGURE 1 was prepared by heat sealing the peripheral edges of a sheet ofpolyethylene film and an overlaid permeable nonwoven fabric of 1 /2denier, viscose rayon staple fibers bonded with a polyvinyl alcoholresin. The interior area of the pouch was rectangular, about 1 /3" by1%". About 1.2 grams of capsules having a urea-formaldehyde shell and afill of perchloroethylene were placed in the pouch prior to finalsealing. The cap sules had diameters between about 300 and 600a andcomprised between about 82 and 88 percent by Weight perchloroethylene.When the pouch was rubbed against fabric material with sufficient forceto crush the capsules therein, with the permeable side against thefabric, food and other stains were removed by the cleaning medium. Thesame results were obtained when the pouch was used to clean stains fromrugs, drapes, upholstery, floors, walls, and other areas;

I claim:

1. A dry applicator pad containing a supply of liquid agent that may bereadily released in controlled amounts by pressure on the pad during useand which is adapted for neat and convenient handling and storage, saidpad comprising a thin flat flexible compressible sealed pouch havingfront and back walls united at their peripheral edges and containingmany individual loose dry pressurerupturable capsules less than 1000microns in diameter,

each comprising a polymeric thin shell filled with said liquid agent, atleast one wall of the pouch including a conformable liquid-permeablefibrous web whereby when the pouch is rubbed in contact with a surfaceof application, liquid agent is freed from capsules by the rubbingpressure and applied.

2. The applicator pad of claim 1 in which the capsules are between about300 and 600 microns in diameter and have an aminoplast polymeric shell.

3. The applicator pad of claim 1 in which the liquid 7 agent is adry-cleaning agent for clothing.

4. A dry applicator pad containing a supply of liquid agent that may bereadily released in controlled amounts by pressure on the pad during useand which is adapted for neat and convenient handling and storage, saidpad comprising a thin flat flexible compressible sealed pouch formed byoverlaid sheets of heat-scalable material sealed together at theirperipheral edges and containing many individual loose drypressure-rupturable capsules between about 300 and 600 microns indiameter, each comprising an aminoplast polymeric shell filled in anamount of 82 percent or more by weight with said liquid agent, one sheetbeing a liquid-impermeable polymeric film and the other a conformableliquid-permeable fibrous material whereby when the pouch is rubbed incontact with a surface of application, liquid agent is freed from thecapsules by the rubbing pressure and applied.

References Cited CHARLES A. WILLMUTH, Primary Examiner.

E. L. ROBERTS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,334,374 August 8 1967 Nathaniel L. Watkins, Jr.

error appears in the above numbered pat- It is hereby certified that tthe said Letters Patent should read as ent requiring correction and thecorrected below.

after "forming" insert the receptable Column 1, line 36,

liquidcolumn 2, line 60,

should comprise a rather thin, after "between" insert about Signed andsealed this 15th day of October 1968 (SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

1. A DRY APPLICATOR PAD CONTAINING A SUPPLY OF LIQUID AGENT THAT MAY BEREDILY RELEASED IN CONTROLLED AMOUNTS BY PRESSURE ON THE PAD DURING USEAND WHICH IS ADAPTED FOR NEAT AND CONVENIENT HANDLING AND STORAGE, SAIDPAD COMPRISING A THIN FLAT FLEXIBLE COMPRESSIBLE SEALED POUCH HAVINGFRONT AND BACK WALLS UNITED AT THEIR PERIPHERAL EDGES AND CONTAININGMANY INDIVIDUAL LOOSE DRY PRESSURERUPTURABLE CAPSULES LESS THAN 1000MICRONS IN DIAMETER, EACH COMPRISING A POLYMERIC THIN SHELL FILLED WITHSAID LIQUID AGENT, AT LEAST ONE WALL OF THE POUCH INCLUDING ACONFORMABLE LIQUID-PERMEABLE FIBROUS WEB WHEREBY WHEN THE POUCH ISRUBBED IN CONTACT WITH A SURFACE OF APPLICATION, LIQUID AGENT IS FREEDFROM CAPSULES BY THE RUBBING PRESSURE AND APPLIED.